This invention relates generally to the field of fiber optic light transmission as used in telephonic and other forms of communication, and more particularly to an improved plug connector and corresponding adapter for use with jacketed cable. Devices of this general type are well known in the art, and are widely used in the field o telecommunication.
Optical fibers in the art normally include a core surrounded by a cladding, also made of optical fiber material, but having a different index of refraction, the core and cladding being enclosed in a flexible jacket of 3 mm. diameter. The core and cladding have a diameter which may be as little as 125 microns. In order to have maximum light transmission between the terminated ends of a pair of communicating cables, alignment both axially and radially of the axis of the cables must be extremely precise, and as close to a coaxial condition as possible. Depending upon the quality of transmission required, these fibers may be used in either single mode or multimode operation.
The advantages of fiber optic transmission are well appreciated in the art, and need not be further elaborated in the present disclosure. However, the problems involved in the finished ends of a pair of optical cables are equally well known, and relate largely to the problem of precise adjustment of the fibers for maximum light transmission therethrough. These problems have been resolved using a variety of coupling constructions, a very commonly used typing of the so-called ST connector. In this construction, each terminated fiber cable is carried by a plug type element, each plug being selectively engaged with a so-called adapter which engages a plug element at either end thereof. The adapter is commonly mounted within an opening in a bulkhead or other wall, and includes means for fixing the adapter against rotation with respect to the bulkhead.
Not surprisingly, the need for a high order of precision is accompanied by higher cost of manufacture. Where interconnections of fiber cables are made in a telephone central office, this added cost may be readily absorbed. Many such interconnections are made as a part of local area networks, or as part of an individual subscriber line where considerations of cost at the time of installation are of significant moment.